pgsql: Use stdbool.h if suitable

Use stdbool.h if suitable

Using the standard bool type provided by C allows some recent compilers
and debuggers to give better diagnostics. Also, some extension code and
third-party headers are increasingly pulling in stdbool.h, so it's
probably saner if everyone uses the same definition.

But PostgreSQL code is not prepared to handle bool of a size other than
1, so we keep our own old definition if we encounter a stdbool.h with a
bool of a different size. (Among current build farm members, this only
applies to old macOS versions on PowerPC.)

To check that the used bool is of the right size, add a static
assertions about size of GinTernaryValue vs bool. This is currently the
only place that assumes that bool and char are of the same size.

Discussion: https://www.postgresql.org/message-id/flat/3a0fe7e1-5ed1-414b-9230-53bbc0ed1f49(at)2ndquadrant(dot)com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9a95a77d9d5d3003d2d67121f2731b6e5fc37336

Modified Files
--------------
src/backend/utils/adt/tsginidx.c | 4 +++-
src/include/access/gin.h | 4 ++--
src/include/c.h | 14 ++++++++++++--
src/include/pg_config.h.win32 | 9 +++++++++
src/pl/plperl/plperl.h | 10 +++++-----
5 files changed, 31 insertions(+), 10 deletions(-)